This invention relates generally to large industrial flow control valves, and more particularly, to multi-jet sleeve valves.
Conventional sleeve valves have been employed to control the flow rate and head pressure of fluids in industrial piping systems. Sleeve valves are often chosen because of their ability to reduce head pressure and control flow rates without creating significant cavitation which can cause excessive noise and premature wear of valve components.
A conventional downflow sleeve valve has a vertically-oriented, generally cylindrical sleeve, and a gate adapted for sliding within the cylindrical sleeve. The sleeve includes an intake coupled to a fluid supply line. The sleeve further includes a discharge nozzle section. The nozzle section is a generally cylindrical tube having a plurality of diverging nozzles arranged in a pattern about a longitudinal axis of the sleeve. The bottom of the sleeve is connected to a base pan that is mounted to the inside bottom of a tank or stilling well. The base pan is a generally cylindrical tube connected at its upper end to the sleeve. Its lower end is closed by a disc-shaped plate welded thereto. A drain pipe extends radially from the base pan and is connected to a drain valve to discharge fluid from the sleeve.
The sleeve valve is operated by axial movement of the gate positioned within the sleeve. The gate is generally cylindrical in shape and has exterior annular channels adjacent its upper and lower ends, and annular seals within the channels. The seals are adapted for sliding sealing engagement with the interior of the sleeve. The gate includes an internal fluid passageway therethrough extending from its upper end to its lower end. The passageway reduces head pressure from fluid upstream of the gate by permitting fluid to flow through the passageway. In other words, when the gate is moved axially upwardly (i.e., upstream), then fluid within the piping system flows through the passageway of the gate such that no significant axial force is exerted on the gate due to head pressure. An actuating stem extends vertically upwardly from the gate and extends through the piping system. Up and down movement of the stem causes up and down movement of the gate. The gate is moveable between open and closed positions. In its closed position, all of the nozzles of the nozzle section are axially between the seals of the gate. The seals seal against fluid flowing from the piping system out the nozzles. In the open position, the gate is positioned such that both of the annular seals of the gate are positioned axially below the nozzles so that fluid flowing downward into the sleeve flows laterally outwardly through the nozzles. The gate may also be positioned somewhat between the open and closed positions to control the rate of fluid flow through the nozzle section. In other words the gate may be positioned so that the upper seal of the gate is below some of the nozzles and positioned above the rest of the nozzles so that fluid flows out only some of the nozzles. To increase fluid flow, the gate is raised (i.e. moved upstream); to decrease fluid flow, the gate is lowered (i.e. moved downstream).
Occasionally, debris accumulates within the gate or in the sleeve valve. The debris is usually larger than the openings of the nozzles and therefore does not flow out the nozzles. The debris may negatively affect the performance of the valve or the flow rate through the piping system and therefore must be removed. A disadvantage of prior art sleeve valves is that the valve must be disassembled to remove the debris. Disassembly of the valve results in considerable effort, cost and downtime.